<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Canvas</title>
    <style type="text/css">
        body {
            text-align: center;
            padding-top: 20px;
        }
        canvas {
            box-shadow: 0 0 10px #333;
            margin: 0 auto;
        }
    </style>
</head>
<body onload="draw()">
    <canvas id="canvas" width="800" height="600">
        你的浏览器太 low 了，请更新~!
    </canvas>

    <script>
        function draw() {
            var canvas = document.getElementById("canvas");
            if (canvas.getContext) {
                // 说明支持当前浏览器，在其中写代码...
                var ctx = canvas.getContext('2d');
            }
        }
    </script>
</body>
</html>
